降雨冲刷条件下含水率变化对堆填黄土沟床侵蚀的影响  

Effect of water content variation on the gully bed erosion of loess landfill under rain scour conditions

作　　者：王之君[1] 马彦杰 刘兴荣[2] 黄金燕 李启润 WANG Zhijun;MA Yanjie;LIU Xingrong;HUANG Jinyan;LI Qirun(College of Energy and Power Engineering,Lanzhou University of Technology,730050,Lanzhou,China;Geological Hazards Prevention Institute,Gansu Academy of Sciences,730000,Lanzhou,China)

机构地区：[1]兰州理工大学能源与动力工程学院,兰州730050 [2]甘肃省科学院地质自然灾害防治研究所,兰州730000

出　　处：《中国水土保持科学》2024年第5期31-40,共10页Science of Soil and Water Conservation

基　　金：国家自然科学基金“黄河上游沙漠泥流水沙耦合成灾机理与优化模型研究”(42167043);甘肃省科学院重点科技研发项目“群发型泥石流灾害放大效应及综合防治技术研究”(2023ZDY F-03);甘肃省科学院重大专项项目“甘肃南部山区溃决型泥石流形成、演化机制及防治关键技术”(2024ZDZ X-02)。

摘　　要：黄土区城市建设造就大量堆填黄土场地,受极端降雨作用影响,水土流失严重。为探究含水率变化对土壤侵蚀的影响,本研究基于野外调查,采用室内直槽概化模型试验,开展堆填黄土沟床模拟降雨冲刷试验研究。结果表明:1)堆填黄土沟床侵蚀过程以水力侵蚀和重力侵蚀交互作用为主。随土体含水率增加,堆填黄土易湿陷、液化,水力侵蚀作用增强;2)沟床侵蚀发育过程中土体含水率和孔隙水压力两者变化规律呈现明显的一致性,土体失稳、侵蚀破坏前后出现大幅度波动,是土体结构破坏及侵蚀滑塌的关键因素;3)随前期降雨引起土体含水率增加,土体抗剪强度下降,水流冲刷沟床易侵蚀破坏,沟床侵蚀速率增大,溯源侵蚀演化速度加快。该研究表明前期降雨引起含水率变化在土壤侵蚀中的影响显著,可为工程堆积体水土流失和土壤侵蚀等研究提供参考。[Background]Lanzhou city has carried out many land construction projects due to urban expansion and formed many landfill loess sites.Its structure is loose and lacks necessary protective measures.Under the action of extreme rainfall,soil erosion is serious.Therefore,it is of great significance to reveal the mechanism of soil erosion under soil-water coupling by exploring the influence of water content change caused by early rainfall on soil erosion.[Methods]Based on the field investigation,this study selected the typical landfill loess site in Lanzhou city to sample,and used the indoor straight channel generalized model test to carry out the simulated rainfall erosion test of the landfill loess gully bed,combined with the soil erosion phenomenon and the volumetric water content,pore water pressure analysis and study.[Results]1)The erosion process of landfilled loess gully bed is dominated by the interaction of hydraulic erosion and gravity erosion.With the increase of soil water content,loess landfill is prone to collapsibility and liquefaction,and hydraulic erosion is enhanced.2)The variation rule of soil water content and pore water pressure during the development of gully bed erosion are obviously consistent,whose significant fluctuations during the soil instability and large erosion damage processes are the key factors for soil structure damage and erosion collapse.3)With the increase in water content of the soil body caused by the previous rainfall,the shear strength of the soil body decreases,the water flow scouring the gully bed is prone to erosion and damage,the erosion rate of the gully bed increases,and the evolution of retroactive erosion is accelerated.[Conclusions]This study shows that the change of water content caused by pre-rainfall has a significant effect on soil erosion.Pre-rainfall will destroy the surface soil erosion and cause the increase of water content,which can effectively weaken the soil strength and aggravate the soil erosion damage.The results are expected to provide a reference in s

关 键 词：堆填黄土 侵蚀机理 体积含水率 孔隙水压力 模型试验 前期降雨 

分 类 号：P642.13[天文地球—工程地质学] S157[天文地球—地质矿产勘探]